Power tongs

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION The power tong, as illustrated in the drawings, includes a frame 10 formed by an upper frame plate 14 and a lower frame plate 16 interconnected by side wall 18 to which these frame plates are bolted.
The frame 10 has an arcuate pipe-side which defines an opening or a throat 20 for receiving a pipe section, typified by drill pipe, casing or other tubular goods used in the drilling and completion of oil and gas wells.
Such pipe section can pass through the throat 20 into a circular opening 21 in the center of the frame.
On opposite sides of the throat or opening 20, and mounted immediately inside the side walls 18 are a pair of arcuate bearing and guide segments 22 and 24.
Each of the arcuate bearing and guide quadrants or segments 22 and 24 is formed on an arc of a circle extending over at least 90.
degree.
of arc, and preferably approximately 120.
degree.
of arc, and each is formed of a block of graphite impregnated polyurethane material, hereinafter described in greater detail.
Each of the arcuate bearing and guide segments 22 and 24 is of generally rectangular cross-section and is provided with a rectangular raceway recess 26 at its radially inner side as illustrated in FIG.
4.
The bearing and guide segments are secured in the position illustrated in FIGS.
3 and 4 by means of a plurality of bolts 28 passed through the upper and lower frame plates 14 and 16 of the housing 10.
The bolts 28 are extended through the segments at central locations aligned along a radial center line of the respective segments.
A door 30 is pivotally mounted to the frame 10 adjacent the throat or opening 20 by means of a hinge pin 32.
The door 30 is openable by the use of a handle 34 to allow the pipe which is to be gripped by the power tongs to be inserted through the throat 20.
One end of a spring loaded piston assembly 36 is attached to the door 30, and the other end of the piston assembly 36 is pivotally attached to the frame in order to retain the door in either an open or a closed position